Re: Valence electrons and energy levels??

There is no (simple) "why" answer to this, beyond "because the atoms are more stable that way." "And why are they more stable?" "Just because."

There are quite a number of answers on our site that address aspects of this problem, but your particular question has no answer, at least not the sort of answer you seem to be seeking. Especially not in terms of the shell model.

(Even if you used the more sophisticated "atomic orbital model" there's still no "why" answer -- electrons go into the 4s orbital before the 3d "just because"! and in fact, the transition metal ion Fe+++ has the configuration 3d5 4s0 while a free, neutral vanadium atom -- with the same number of electrons -- has the configuration 3d3 4s2.)

                                                    Dan Berger
                                                    MadSci Administrator